Transmission lines play an important role in many phases of radio communications. In particular, stripline resonators, microstrip circuits, high speed conductive lines, etc. are used extensively in modern day radios. Some of the major technical problems encountered in implementing transmission lines in multilayer circuit boards are the delay effects, and dielectric losses caused by the dielectric material. A need for dielectric materials having lower dielectric constants is required when implementing certain types of transmission line structures. Propagation delays and dielectric losses can be lowered by utilizing dielectric materials with lower dielectric constants.
A major drawback in utilizing materials with low dielectric constants is that they are normally much more expensive than the standard glass epoxies used in modern multilayer circuit boards. A particular group of materials which have lower dielectric constants than standard glass epoxies are fluroplastics (i.e. one specific type is polytetrafluoroethylene, or as it is more commonly known, TEFLON.TM., manufactured by Dupont, Inc.). Fluroplastics have dielectric constants under 3.0 to 6.0 for conventional glass epoxy mixtures. The major problems encountered when using fluroplastics such as TEFLON.TM. as dielectric substrate material is their high cost, and their difficulty in bonding to other substrate materials such as glass epoxies. Typically, the fluroplastic surface has to be chemically treated in order to accept bonding to other materials such as glass epoxies, making the process costlier to produce. A need exists in the art for the cost effective use and manufacture of fluroplastic dielectrics in transmission line structures, and especially in multilayer circuit boards.